You asked for "thoughts." I would think if someone were to make a comment about your lights, then you would consider that a "thought." Would you rather that someone simply reply "No" to answer your question about low nutrients, without much explanation?
I think lighting with nems is more important than nutrient load. The zooxanthellae within the nem can oftentimes determine the color -- or perceived color -- of a nem. Low light = dead zoax = bleached nem. With gigs, they like a lot of light, and those under a lot of light tend to be browner (a majority of the zoox is typically brown in gigs) but the tips of the gig, where the color is, can also be brighter.
What do you mean by the color could be better? Do you mean that it looked better at the store? Did it change color? In terms of overall color, nems can only look "so good" meaning that it will never drastically change color. For example, a typical green haddoni will never turn into a florescent green haddoni.
Typically if your corals are doing well, so should your gig. They can easily survive and are happy in low nutrient tanks, especially if they're fed (though they don't need to be). The main culprit of a color change could definitely be your LEDs. I've witnessed it myself when I switched from halides to LEDs. While my gig was happy, it went from a brown to more of a mauve -- this probably has more to do with how the LED light reflected than a drastic shift, but it did change nonetheless. This also occurs when corals adjust from halides to LEDs -- some colors get better, but others get worse.
